Recovery of lead and cadmium ions from metal-loaded biomass of wild cocoyam ( Caladium bicolor  ) using acidic, basic and neutral eluent solutions

The effects of acidic, basic and neutral reagents on the recovery of Pb²⁺ and Cd²⁺ from metal-loaded biomass of wild cocoyam (C. bicolor) were investigated by eluting the biomass in five successive cycles using 0.01 M HCl, 0.1 M HCl, 0.01 M NaOH, 0.1 M NaOH and distilled water at different contact times. The data showed that the ease of metal ion recovery from metal -loaded biomass by the eluent solutions is of the order 0.01 M HCl > 0.1 M HCl > 0.01 M NaOH > 0.1 M NaOH > distilled water. Over 94% Pb²⁺ and 74% Cd²⁺ of the initially adsorbed metals were recovered by 0.01 M HCl, while < 20% of both metals was recovered by basic reagent. Distilled water recovered less than 9% of both metal ions from the biomass. Macroscopic changes were also observed as the concentration of recovery reagent increased. This study has demonstrated that the selection of a recovery reagent for metal ions on a biomaterial should give consideration to the reusability of the biomass.

Keywords
cocoyam, desorption, heavy metals removal, metal recovery, water treatment.